Date post: | 06-Apr-2018 |
Category: |
Documents |
Upload: | mikaela-mennen |
View: | 218 times |
Download: | 0 times |
of 40
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
1/40
Solar Production of Fuels and Chemicals;is there a cost-effective path forward?
1
Bi Picture
Outline
Solar Energy Conversion: What Works, What Doesnt , and Why
Strategies and Tactics: Potentially Cost-Effective ArtificialPhotosynthetic Processes
Im roved Li ht Absorbers and Electrocatal sts
2
Beyond Water Splitting
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
2/40
Radiation From Thermonuclear Reactions Has BeenAnd Always Will Be The Most Important Source
Of Energy For The Earth and Human Beings
Societal prosperity through the 19thcentury was powered
by renewable biomass.
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
3/40
5
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
4/40
Mtoe/year
20117 billion~ 17 TW
Prosperity + Population Demand
19122 billion people
~ 1 TW
Societal prosperity through the 19thcentury was powered by renewable biomass. Global prosperity in the 20th Century was possible due to the availability of large quantities
of inexpensive fossil hydrocarbon resources.
Global prosperity in the 22ndcentury will depend on availability of enormous quantities ofsustainable energy resources (32+TW) and/or significant unprecedented population control.
The 21st Century Better Figure Out How to Get Us There.
Low cost, solar derived, hydrocarbonfuels have provided unprecedentedopportunities for global egalitarian
prosperity.
8
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
5/40
$ 63,000,000,000,000~ $120/GJ
512,000,000,000 GigaJoules
9
Yes, there is a limit on how much we can spend
Society can not spend (for long) more on energy
than the value createdConservation of Money
World GDP 2010 ~ $63 Trillion/y(US/Ger/China/India 14/3.6/6/1.5)
~
World Gross Domestic Product (GDP)
(US/Ger/China/India 3.5/0.6/3.5/0.9)
Absolute Spending Limit (GDP/Energy Use)U.S. $120/GJ Germany $190/GJChina $50/GJ India $50/GJ
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
6/40
Fraction of U.S. GDP
Max Total Spending on Energy ~ 10-15% of GDP< $5 -15/GJ: the lower the better.
spen on energy
11
Raising the price of energy meansthe money must come from somewhere else.
Decreased Prosperity.
During times of relative economic stability and increasing
world prosperity food and fuel are inexpensive< 10-15% GDP
Food ~ $5 - 15/GJ and Fuel ~ $2 - 15/GJ
Corn $2.00 /bushel $7.90 /GJ
Rice $2.00 /cwt $4.40 /GJ
Oil $85.00 /barrel $13.94 /GJ
Coal $50.00 /ton $1.70 /GJ
Natural
4.00 MMBTU . . .
Gasoline $2.50 /Gallon $20.00 /GJ
Electricity $0.05 /kWhr $14.00 /GJ
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
7/40
Bad Things Happen WhenFood and/or fuel > $15/GJ
2008Oil @ $150/bbl ~ $24/GJea us e ~
Electricity @ $0.15/kW-hr = $30/GJ
Cause or Effect ?
Here we go again?
14
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
8/40
Where do most people (including scientists) think the money
will come from for new sources of sustainable energy?
15
Sustainable = Environmental and Economical
(non-toxic, renewable) (< $5 - 15/GJ)
n1
Annual Net Revenue($)Total Capital($)
(1 discount rate)
nn
year
Production Cost
nProduct Price1
n1
Total Capital($) 1Product Price(1- )
System Output(GJ/y) (1 discount rate)
1~ 8 - 3 for DR~ 10 - 30%, n~10 years
(1 discount rate)
Total Capit
n
year
n
year
Production Cost
Product Price
al($)~ 15($/GJ) (1- ) * 5 ~ 60($ / / )
System Output(GJ/y) y GJ y
16
Energy Production Cost
Energy Product PriceTotal Capital($/Watt) 1.8 *(1 - )
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
9/40
Science and Engineering have provided society with low costprocesses for economically sustainable energy production.
$0.25 - 1/Watt
$1-3/Watt
Solar Wind Electricity
EnvironmentallyAnd EconomicallySustainably ?
$0.5-1/Watt
2050
~ 30 TWfrom where?
Solar Conversion Processes
200 W/m2 ~ 1 mMoles photons/m2s
Inputs Outputs
18
Output Value - Input Costs - CapX - OpX > 0
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
10/40
How to use solar radiation ?
Inputs Outputs
19
Utilization of electrochemical potential from electronic excitations (e-,h+) EMF Photovoltaics (e-,h+) EMF, EChem Photosynthesis (e-,h+) EMF, ThermalWind, Hydro, Solar-Thermal
Earth as a conversion system (e-,h+) EMF, Thermal Wind, Hydro (e-,h+) EMF, EChem Photosynthesis
~ 1% Wind
~ 10% Hydro
20
, omass, t e
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
11/40
Cost-Effective Solar Energy Conversion: Wind and Hydro-Power
21
Why Solar-to-Chemical Photosynthesis Works
m
=0.1%
0.2 J/s-m2
~ - ~ -
22
0.0063 GJ/y-m2
~ $ 0.1/m2 year Revenue
Because, it costs farmers less than $0.1/m2-year to grow biomass,AND only because they dont need to produce very much of it.
~ 200 Watts/person
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
12/40
Why Solar-to-Electricity Does Not Work
m
~ 10%
20 J/s-m2Electricity Value ~ $15/GJ
23
0.63 GJ/y-m2
~ $ 10/y-m2 Revenue
A modern cell system installed @ $5/Wpeak
Capital Cost ~ $500/m2
Why $500/m2
Its a wild world out there
$$$
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
13/40
price ($)
per m2
To be cost effective on capital alone, a solar convertermust cost less than ~ $40/m2 for ~10% and less than ~ $400/m2@ =100%
no or an
paint (3 mils) 0.6
plastic (6 mils PE) 1.1
plywood 6.5
astro-turf 8.2
sod lawn 8.6
vinyl flooring 10.8
1" concrete 13.5+ lots of
land.roof tile 64.6
Asphalt road 172.2
Si Solar Cell($5/W) 500.0
Home Construction 1500.0
Only VERY Inexpensive Systems
26
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
14/40
2009
27
Google: Grid Parity?
28https://docs.google.com/present/view?id=dfhw7d9z_0gtk9bsgc&pli=1
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
15/40
29
30
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
16/40
Wealthy nations (with low GDP growth) tolerate economicallyunsustainable renewables such as solar cells because
they are balanced by relatively low cost fossil/nuclear/wind
China ~ 3.5 TW
U.S. ~ 3.5 TW Germany~ 0.6 TW
31
Chemical sciences and engineering must create optionsfor massive quantities of sustainable sources
of energy that are affordable by all people
Cost reductions over the last decade
32
are arge y ue to use o ncreas ngnumbers of low wage workers notimproved technology. The majorityof the costs are paid from taxpayersubsidies.
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
17/40
33
~1780
~1880 Adams&Day, Fritts
Se Solar Cells 1-2% efficiency)
More than
100 years of
Development
No Significant
Cost-Effective
Applications
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
18/40
C*(e-,h+)
e-
h+
A
D
e-
h+
A-
What about Solar-to-Chemical ? chemical potential
CC
D+
2e- + 2H+ +xCO2 CxH2OzH2O + 2h
+ O2 + 2H
+
ReducingPotential
35
Growth Driven By Unsustainable Economics
36
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
19/40
Growth Driven By Unsustainable Economics
Biodiesel
37
Can Man Beat Nature ? Artificial Photosynthesis
G. Ciamician, Science 1912
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
20/402
Solar Energy, Volume 2, Issue 2, April1958
Semiconductor Photoelectrodes
E
RED
Photocathode
h+
+ +
OX
-
Photoanode
+
h
RED
OX
E
n-type SC
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
21/402
SuspendedPVplatelets 1981
Hydrogen
Platelets
N-type semiconductorp-typesemiconductor
Ohmiccontact
Platelet
100 + Years of
Photoelectrocatalysis (PEC)Science has provided efficient systemsbut not cost-effective energy production
TiO2 PEC
42
PEC AirPurifier
Mosquito Trap
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
22/402
Going Forward: Strategies and TacticsHow to do the right thing and get others to pay for it.
Options:1) Scare them into it.2) Keep making promises that are impossible
to keep.3) Create options that, if tough problems are
creatively solved, might ultimately proveeconomically sustainable.
43
Is there a cost-effective solarPEC Process that can
make use of the material system?
Find and understand anefficient PEC material system
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
23/402
ConceptualEngineeringProcessModels
Photoelectrodes = PV ($$) + electrolyzer($$)
Un-biasedPhotoelectrode(s)
Chemically biasedPhotoelectrode(s)
Electrically biasedPhotoelectrode(s)
BottomUpvsTopDown
donotunderestimatetheengineeringDesign a conceptual cost-effective
Solar Chemical Process
Can a material system befound that meets the
minimum requirements ?
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
24/402
Artificial Photosynthesis
47
~ 10%~ 0.1 %~ 0.1 %
ConceptualEngineeringProcessModels
Photoelectrodes = PV ($$) + electrolyzer($$)
Un-biasedPhotoelectrode(s)
Chemically biasedPhotoelectrode(s)
Electrically biasedPhotoelectrode(s)
-+A
-D
Split Z-SchemeSlurry Photoreactor
Single TankSlurry Photoreactor
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
25/402
Today,thereisonlyoneknownsystemforsolarfuels
(hydrogen)whichmight makeeconomicsense.
ASSUMES that a stable, =10% slurry material exists
Only slurry-based
James B, Baum G, Perez J, B.K. Technoeconomic Analysis of Photoelectrochemical(PEC) Hydrogen Production. Analysis22201, (2009).
systems might meet basiceconomic targets. $6/GJ
h
Can we do better than Nature?
What structures should we make and calculate
D-
D
A
A-
e-
e-
50
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
26/402
Hybrid PEC NanoreactorsLow cost inorganic semiconductor based heterostructures
Our Strategy
Theory New/improved low cost semiconductors Understanding of excitation/separation/
h+
e-
h A-AD-
- , ,Interface charge transfer. RecombinationElectrocatalysis
Synthesis/Experiment
New/improved low cost, high-quality semiconductors Heterostructures Diffusion barrier/encapsulation
AA-Zn2+ Zno -0.76
-0.26V3+ V2+
Approach
h
Maximize Stored SolarChemical Potential
D-
DA
A-
2I-1I2 0.54
D- D
(CnHm)OH(CnHm)O 0.6
2H+ H2 0.00
AgCl Cl-+Ago
0.34
0.22
Cu2+ Cuo
CO2 CH4 0.17
1) Identify cost effective optimal solar absorbingsemiconductor Egap~ 1eV systems with IQE >90%.
h+
e-
H2O2H++1/2O2 1.23
2Br-1Br2 1.07
Fe2+Fe3+ 0.77
2Cl-1Cl2 1.36
2) Select and match best practical redox systems thatcould provide stored energy G ~ 0.9*Egap
3) Maximize selective kinetics (minimize back reaction)
4) Determine means for stabilizing the material in theredox system
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
27/402
HighThroughputMethodology
Al2O33000
Al2O31500
V800
V1600
SnO24800
4000
1000
La2O3
4000
1000
Y2O3
4000
1000
MgO
4000
1000
SrCO3
Sample: 826962
Theory Guided
0530
0260
0240
0250Eu2O3 Tb4O7 Tm2O3 CeO2
Science279, 837-839 (1998)
Library Design:Diversity in CompositionDiversity in Synthesis
Rapid Synthesis and Processing:Electrochemical DepositionPVD, Ink Jet, Solgel,Parallel vs Rapid SerialSmall vs Large Element Size
High-Throughput Screening:Optical, Chemo-opticalPhotoelectrochemicalGC-MS
Start with a known reasonable host Try to make it better
Make efficient materialmore stable
Bak et. al., Int. J. Hydrogen Energy,vol 27 (2002) 991-1022
ZnnXmO
45
WnXmOp
H2O/H2
O2/H2O
1.23 eV
Cu2O TiO2 Electrolyte
Eabs(eV)
- 4
- 5
- 6
- 7
- 8
- 3
ENHE(eV)
0
+1
+2
+3
- 1
- 2
2.0 eV
3.0 eV
0.30
Cu2O/XOn
0 20 40 60 80 1000
1
2
3
4
1520253035
Photocurrent(A/cm
2)
[Mo]
1V bias
zero bias
J. Combi. Chem. 4(6), 573-578, 2002
4 6 8 10 120.10
0.15
0.20
0.25
Photocurrent(mA/cm
2)
pH
J. Comb. Chem., 7, 264-271, (2005)
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
28/402
Doped: ZnO
TheScienceofSynthesis
55
J. Comb. Chem., 7, 264-271, (2005)
WO3
15202530354045
rent(A/cm
2) 1V bias
WnXmOp
MoO3
MoO3
W0 2Mo0 8O3
56
0 20 40 60 80 1000
1
2
3
Photocur
[Mo]
zero bias
J. Combi. Chem. 4(6), 573-578, 20025 00 5 50 6 00 6 50 7 00 7 50 8 00 8 50 9 00 9 50 1 00 0 10 50 1 10 0
W0.2Mo0.8O3
W0.3
Mo0.7
O3
W0.5
Mo0.5
O3
W0.7
Mo0.3
O3
W0.8
Mo0.2
O3
WO3
Intensity(a.u.)
Raman Shift (cm-1)
20 22 24 26 28 30
. .
W0.5Mo0.5O3
W0.8Mo0.2O3
WO3
Intensity(a.u.)
2
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
29/402
In spite of decades of research, there is no evidence thatwide gap oxides (TiO2, WO3, ZnO, ) can be modified to serveas efficient solar absorbing hosts. Fe ? Cu ?
Fe2O3
n-Type Indirect Bandgap 2 - 2.2 eV
40% solar spectrum absorbed
Globally scalable
Abundant, inexpensive
Non-toxic
Photo-stable against corrosion
Mott Insulator (Poor carrier transport )
Anisotropic conductivity Low electrocatalytic activity
TheoryGuidedExperimentationUndoped Fe3+
Fe2O3 Pt4+ doped Cr+3 doped Al+3 doped
58
Flat Conduction band large effective mass, poor conductivity.1) Majority Carrier Donor Concentration (traditional doping)2) Create Impurity bands which have smaller mass3) Break C-T Mott Insulator, spin forbidden electron transport
U=5.7eV12Fe+18O
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
30/403
CharacterizationofsubstitutedFe2O3
Bg=2.1 eV
J. Phys Chem C. 20(12),3803, (2008)
Chem. Mater., 20, 38033805, (2008)
Energy Env. Sci. 4,1020, (2011) 1%Ti
Optical properties show little change with dopants Higher valence dopants (n-dope) helps Isovalant substitutions with large cation size differences (strain) helps
De l a f o ss i t e s (Cu M X 2)
Cu+
Theoretical bandgap
Direct: 3.0 eV
Indirect: 2.1 eV
Experimental bandgap: 1.3 eV
2r
In general, poor efficiency.
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
31/403
Phosphides(start with an efficient material and make it more stable)
Easytomake(fromlibrariesofoxides) MxOy +H3PO4 ; H2 at900C
.
Easy to break Zn3P2 + 6H2O 2PH3 + 3Zn(OH)2
Strategy -> keep
H+
Na6 [HxMyOz] + NH4HPO4MPOx + NH4OH +NaOH +H2O
H2 at 900 C
FeP InP Zn3P2 NixPy WP MoP
t em sa e
Sulfides (SnS)
ElectrodepositedFilm powder
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
32/403
Identification of efficient, stable, cost effective solarabsorbing materials remains
the #1 challenge for solar energy PEC
Work to date with all oxides has been discouraging.
- ,enough. The common wide gap oxide semiconductors (TiO2, ZnO, WO3)will not work as absorbers for solar fuel applications.
- Iron oxides are intrinsically poor candidates for solar PEC applications
TiO2
63
and in spite of attempts to improve their properties they remain far tooinefficient by 10-100x.
Sulfides and Phosphides Deserve More Attention
Dont forget Si !
Silicon
Fe2O3 Last oxide hope CuxO
TheoryGuidedIdentificationofActive,Stable,
andSelective
Electrocatalysts
h+
e-
h D
D-2H+
HIn situ membrane
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
33/403
65
Pt-Au Alloy Nanoparticles for ORR
Slope ~ ne
66
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
34/403
Co/AuFe/Ni
Bimetallic OER Electrocataysts
CoAu
67
Electrochem.Com. 11 (2009) 11501153
u
Choice of the electrocatalyst assumes you know the reaction you want.
2H+ H2AA-
What is the best form of the chemical potential product?
H2 fast, separable, easily reacted (H2+ CO2CH4)
1) High efficiency, cost-effective absorbers, Egap~ 1eV.2) Identify stable redox chemistry that can be integrated into a major
chemical cycle.
10
12
14
16
18
Zero BiasNaOHGlycerolErythritolXylitol
(%)
D- D
(CnHm)OH(CnHm)O2 electrodes 1 sun
Ti Doped Fe2O3
H2S2H++ S
2HBr2H++ Br2
Avoid zero value products
350 400 450 500 550 600
0
2
4
6
8IPCE
Wavelength (nm)
H2O2H++1/2 O2
2HCl2H++ Cl2
Get over water splitting!
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
35/403
The formation of adsorbed OOH is limitingand only at high electrode potential is thisstep downhill in free energy. The processtakes place on an oxidized surface.Ox en evolution should start at E>1.8 V
69
Functional Nanoparticulate Heterostructures
Fe2O3@ZrO2
7010 nm
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
36/403
Hybrid PEC NanoreactorsLow cost inorganic semiconductor based
heterostructures
Al2O3
Absorber
Ag
(OhmicContact)
h+
e
Oxidizing
reactant
Reduced
product
AuorPt(Schottkycontact)
Reducing
agent
Oxidized
product
Mubeen J. HussainiFrancesca Toma
Martin MoscovitsGalen Stucky
NiO
AAb
Electrodeposited Heterojunction in Porous Alumina
CdSe
Au
TiO2
l2O3
sorber
Mubeen J. HussainiFrancesca TomaMartin MoscovitsGalen Stucky
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
37/403
Large Scale, Cost Effective Processes Are Typically Integrated
Large Scale, Cost Effective Processes Are Typically Integrated
Process Alternative: CnHmOz H2+ CO2
(CnHm)OH + h+(CnHm)O + H
+
2e- + 2H+ H2
2
Biomass orWastewater
CO2
X-ols
CatalystRegeneration
Reactor SeparationTreatmentSeparation
~ 1 kg/person/day organic waste (~ 1 TW )
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
38/403
2e- + 2H+ H22Br-1Br2
Large Scale, Cost Effective Processes Are Typically IntegratedExample Process Alternative: 2HBr H2+ Br2
Biomass
Regeneration
O2 + HBr Br2 + H2O
Water Air
HBrBr2
Activation
CH4 + Br2 CH3-Br + HBr
Coupling
CH3-Br Gasoline + HBrBioMethane Gasoline
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
39/403
77
Net Reaction: 8CH4 + (16/ C8H16 + 8H2 (Ideal)
Summary
Todaytherearenosignificant,costeffective,manmadesolarconversionprocessesbecausenoefficient,stable,scalable,andcosteffectiveabsorbingmaterialsystemisknown.
Recentadvancesintheory,complexsurfaces,andsynthesisofnovelmaterialsmayhavesignificantimpactifdirectedwisely.
Watersplittingmayormaynoteverbecosteffective,buttherearepotentiallymanyothersolartochemicalconversionsthatmightbemorecosteffectiveandultimatelymoreusefultomankind. Thesystemmatters,manycanneverwork.
Fundamentallyproductionofchemicalfuelsfromsolarenergyatlessthan$15/GJispossible,practicallyitisveryverydifficult.
Thinkoutsidetheboxorwewillnotsucceed
8/3/2019 2011 McFarland IEE UCSB Solar Chemical Conversion
40/40
an ou
Collaborators: Alan Kleiman, Yong-Sheng Hu, PengZhang, Nirala Singh, Galen Stucky, Eric McFarland